That post is not very informative and not very well structured. It also contains some misunderstandings.

Oscillation generated by the mirror up movement is critical and may affect the image, but oscillation caused by the mirror down has no relevance unless the shutter is opened again before the oscillation died out.

The same oscillation is causing more problems in a camera with less mass, like the D7000 than a camera with more mass, like the D300s. In other words, even if the D7000 is better damped it may still be more critical and worse than the D300s. I am not saying this is the case, but it can be.

Measuring the oscillation can be done easier, you don't really need anything else than a high speed video capable camera. Just remove the lens and take a movie of the mirror flipping up. You will see the oscillation and can measure the time for how long it is oscillating.